Mechanism and method for yarn-retrieval control

ABSTRACT

In the end-down servicing of a textile spinning frame, wherein a suction head or other yarn retrieving means movable with the traversing ring rail is disposed adjacent the surface of yarn wound upon a spindle-mounted bobbin above the spinning ring encircling such bobbin, the yarn-retrieving means is actuated when the ring rail is at a predetermined desired location within its traverse. The location, which can be adjustably varied, is preferably adjacent the bottom of a downward traverse of the ring rail. Deactuation of the retrieval means preferably occurs after lapse of a predetermined desired time interval. The bobbin-yarn package is subjected to yarn-retrieving forces for only a minimum period of time, and a sufficient but not excessive length of yarn is retrieved.

Unite States Escursell-Prat atent [54] MECHANISM AND METHOD FOR YARN-RETRIEVAL CONTROL [72] Inventor: Roberto Escursell-Prat, 105 4., 1.", Barcelona 6, Spain [22] Filed: Oct. 1, 1969 [21] Appl. No.: 862,722

[ 1 Feb. 15, 1972 Primary Examiner-Stanley N. Gilreath Assistant Examiner-Wemcr H. Schroeder Attorney-Hunt, Heard & Rhodes [57] ABSTRACT 1n the end-down servicing of a textile spinning frame. wherein a suction head or other yarn retrieving means movable with the traversing ring rail is disposed adjacent the surface of yarn wound upon a spindle-mounted bobbin above the spinning ring encircling such bobbin, the yarn-retrieving means is actuated when the ring rail is at a predetennined desired location within its traverse. The location, which can be adjustably varied, is preferably adjacent the bottom of a downward traverse of the ring rail. Deactuation of the retrieval means preferably occurs after lapse of a predetermined desired time interval. The bobbin yarn package is subjected to yamretrieving forces for only a minimum period of time, and a sufficient but not excessive length of yarn is retrieved.

12 Claims, 4 Drawing Figures PATENTEUFEH 15 m2 3.641.? 5 8 INVENTOR I ROBERTO ESCURSELL p ATTORNEYS MECHANISM AND METHOD FOR YARN-RETRIEVAL CONTROL BACKGROUND OF THE INVENTION The term "yarn" as used herein is intended to encompass all types of threads, rovings, slivers, filaments, yarns and the like.

It is known to rejoin, replace or otherwise piece" broken yarn at a delivery of a textile spinning frame, or like machine of the ring-traveler type, by automatic piecing apparatus: see, e.g., US. Pat. No. Re. 26,230 and Japanese Patent Publication No. 4820/66. Such apparatus frequently includes a patrolling carriage which is automatically stopped adjacent any delivery of a spinning frame where there exists an "end-down" condition by reason of yarn breakage. Normal winding rotation of the bobbin-yarn package at such delivery may then be reversed, as by engaging the spindle seating such package with a disc rotating in the appropriate direction, while a length of yarn is withdrawn from the package by suction or other suitable yarn-retrieving means. The retrieved bobbin yarn may then be traveler-threaded and joined in any one of various possible ways with the roving yarn issuing from the delivery rolls of the spinning frame at the delivery in question.

During the yarn-retrieving operation, the suction head or other retrieving means preferably is supported directly or indirectly by the vertically traversing ring rail of the spinning frame, immediately above the spinning ring at the delivery being serviced, for vertical movement in unison with the rail and ring. This location is preferred since the free end of the broken yarn is most likely to be disposed upon the chase-surface of the bobbin yarn package encircled and traversed by the ring. Operation of the suction head or other retrieving means has heretofore been commenced without regard to the particular traverse-position then occupied by the ring rail supporting the same, and has been continued for a specific time interval hopefully deemed proper for the suction head to, first, locate and retrieve the free end of the yarn upon the package and, secondly, to withdraw from the unwinding package a succeeding yarn segment just sufficient in length for subsequently ensuing operations in the piecing cycle. In view of the fact that the precise vertical position of the yarn end upon the chasesurface of the package is purely a matter of chance, the foregoing procedure does not reliably result in retrieval of a yarn segment of the desired length.

Assume, for example, that it requires time intervals for the ring rail to complete one traverse (i.e., one vertical stroke of its chase-movement) and six to eight time intervals for the suction or other retrieving means to withdraw a yarn segment of the desired length following initial retrieval of the yarn end. If the suction or other retrieving means is actuated when it and the ring rail are adjacent the top of a traverse, and such actuation is programmed to continue for 16 to 18 time intervals, a yarn segment of the desired length would be retrieved if the yarn end happened to be adjacent the bottom of the chase-surface of the yarn package. If, however, the yarn end happened to be disposed adjacent the top of such chase-surface, such that it were retrieved immediately upon actuation of the suction or other means, the withdrawn yarn segment would be over twice the desired length. This would be wasteful and could also impede the overall efficiency and performance of the piecing cycle. Reduction of the actuation time to six to eight time intervals could produce equally unsatisfactory results. If the yarn end were located adjacent the bottom of the chase-surface of the package, and actuation of the suction or other retrieving means for such a reduced time interval were commenced while the ring rail was adjacent the top of its traverse, the suction or other retrieving forces would have stopped before reaching the elevation of the yarn end. In such a case, no yarn whatsoever would be withdrawn from the bobbin and the entire piecing endeavor would fail. The same result would ensue if the yarn end was retrieved, but actuation terminated before withdrawal of a yarn-segment of the necessary length.

SUMMARY OF THE INVENTION The present invention provides a method and apparatus for so controlling the suction or other yarn-retrieving operation as to more reliably insure the retrieval of a yarn segment of the desired length, and also as to minimize the time during which the bobbin-yarn package is subjected to the action of the yarn retriever. If a brush or some similar means other than suction is employed for yarn retrieval, the latter factor assumes particular significance, in view of the possibility of the yarn deteriorating or being damaged if subjected over an extended period of time to the retrieving forces.

The method and mechanism of the invention coordinate actuation of the yarn-retrieving means with the traverse position of the ring rail of the spinning frame, and therefore with the traverse position of the suction head or other yarn-retrieving implement then movable in unison with the ring rail above the spinning ring at the frame-delivery being serviced by the piecing apparatus. A preferred embodiment of the mechanism of the invention is readily adjustable so as to afford the capability for actuation of the yam-retrieval means when the ring rail is at any desired location in its traverse. Preferably, however, actuation occurs when the ring rail is moving toward and closely adjacent the bottom of its traverse. This insures that the suction inlet or other operative element of the yarn-retrieval means, which element will usually have a height equal to or greater than the height of the chase-surface upon the adjacent bobbin-yarn package, will immediately following actuation direct yarn-retrieving forces upon the full vertical extent of the packages chase-surface and therefore upon the yarn end upon such surface, irrespective of the end's precise elevation. Since the yarn end will be promptly retrieved, the retrieving means can be deactuated after a predetermined time lapse, eight time intervals in the previously mentioned illustration, with the assurance that a yarn segment of the desired length has been withdrawn.

While the method and apparatus preferably provide for deactuation of the yarn-retrieving means after the lapse of a predetermined time interval following actuation thereof, as noted above, principles of the invention are also applicable to yarn-retrieving operations where deactuation is in response to photoelectrically or otherwise sensed retrieval of a yarn segment of desired length. Similarly, while yarn retrieval by suction is preferred and is described hereinafter, the invention in its broader aspects is not restricted to only suction-retrieval.

The foregoing and other features and advantages of the invention will be apparent from the following description of an illustrative embodiment thereof, which should be read in conjunction with the accompanying drawing, in which:

FIG. I is a fragmentary and somewhat schematic side elevational view, partially in section and partially broken away, of a bobbin-yarn package encircled by the rail-mounted spinning ring of a spinning frame being serviced by the suction head of an automatic yarn-piecing apparatus including a control mechanism embodying the invention;

FIG. 2 is a plan view taken from FIG. 1;

FIG. 3 is an enlarged horizontal section taken substantially along the line 3-3 of FIG. 1 through part of the control mechanism; and

FIG. 4 is a wiring diagram of the electrical circuit associated with and forming part of the control mechanism.

In FIGS. 1 and 2, the numeral 10 designates the ring rail of a conventional textile spinning frame, while the numeral 16 designates the suction head of yarn-retrieving means carried by and forming part of automatic piecing apparatus servicing such spinning frame. As is well known to those skilled in the art, ring rail 10 is during operation moved vertically by the builder-cam and pick-motion mechanisms of the spinning frame to guide yarn onto spindle-mounted bobbins encircled by traveler-mounting spinning rings carried by rail 10. FIGS. 1 and 2 show the bobbin-yarn package 12 and spinning ring 14 of one of the frames deliveries at which an end-down" or broken yarn condition exists. When the yarn package 12 being formed is of the filling-wind type, as shown, rail may reciprocate through a constant traverse of, say, approximately 2 inches as it is moved slowly and continuously from a lowermost and to an uppermost position relative to the spindle (not shown) supporting package 12. As shown in FIG. 1, rail 10 is approximately midway through a downward traverse, as indicated by the directional arrow and by the rails location relative to the upper and lower extremities of the sloping chasesurface of bobbin-yarn package 12.

As will also be appreciated by those skilled in the art, the piecing apparatus servicing the spinning frame may include a patrolling carriage positioned forwardly and movable longitudinally thereof to any of its deliveries requiring servicing by reason of an end-down condition. The carriages servicing mechanisms include means for retrieving, from the deliverys bobbin-yarn package, first the free end of the yarn upon such package and then a succeeding yarn segment of desired length sufficient for subsequently ensuing operations in the piecing cycle. The yarn-retrieving means may include a suction head 16, connected to a selectively actuable suction source within the carriage by means of a flexible hose or the like (not shown), which during operation is supported by or otherwise made movable in unison with ring rail 10 of the spinning frame immediately above ring 14 and closely adjacent the chase-sur face of the package 12 encircled by such ring. The inlet of suction head 16 faces package 12 and preferably has a height at least equal to the elevation of the packages chase-surface, so that such inlet will completely span the vertical extent of the chase-surfaceupon which the free end of the broken yarn is most likely to be locatedwhen ring rail 10 is at the bottom of a traverse.

Due to the random location of the yarn end upon the chasesurface of package 12, actuation of the suction-retrieving means without regard to the vertical position then occupied by ring rail 10 at times produces the unsatisfactory results discussed previously herein. The present invention, in contrast, coordinates yarn retrieval and movement of ring rail 10, and provides for actuation of the yarn retrieval means when ring rail 10 is at any desired and predetermined location in its vertical traversing movement. The control mechanism achieving the foregoing results generally includes a switch element 18 and cooperating actuating element 20; means including a bracket 22 mounting actuating element 20 for traversing vertical movement in unison with ring rail 10 and for adjustive vertical movement relative to the ring rail; means including an upright rod 24 mounting switch element 18 for actuation at desired times by element 20 and for vertical displacement in unison with ring rail 10 under the impetus of the pick-motion mechanism of the spinning frame; means including an upper bracket arm 26 and lower bracket arm 28 for so displacing switch element 18; and a control circuit (FIG. 4) including switch element 18 and responsive to actuation thereof for first actuating the suction-retrieving means of the piecing apparatus and for thereafter deactuating the same.

As is best shown in FIGS. 1 and 2, bracket 22 comprises a post 22' secured adjacent its lower end, as by rollers 23, to the forward part of ring rail 10 for movement longitudinally thereof with the movable carriage of the piecing apparatus (not shown) and for vertical traversing movement in unison with rail 10. Arms 26, 28 are carried by or formed integral with the upper portion of post 22', and extend generally horizontally forwardly therefrom in vertically spaced relationship to each other, the distance between arms 26, 28 being approximately equal to the height of a traverse of ring rail 10. Vertically aligned bores of arms 26, 28 receive the upper end portion of rod 24, which is rigidly secured at its lower end to the movable carriage of the piecing apparatus (not shown) in laterally offset relationship to its suction head 16, and thus connect bracket 22 for movement with the piecing apparatus to a delivery of the spinning frame requiring servicing,

intermediate arms 26 and 28, collars 30, 32 respectively encircle post 22' and rod 24 for vertical sliding movement longitudinally thereof (FIG. 3). Collar 32 is formed of material having such a magnetic or frictional attraction with rod 24 as to maintain whatever position it might occupy upon the rod until positively displaced from such position, while collar 30 is releasably secured in any desired position of a vertical adjustment by means of a lock-bolt 34 carried thereby and engaging post 22'. Switch 18, which is carried by collar 32 and includes a roller-arm 18' extending therefrom toward the spinning frame, is of a snap-action type momentarily actuated upon movement of arm 18' in one direction only, illustratively downward movement. Fingerlike actuating element 20 is carried by collar 30 and extends forwardly therefrom for engagement with roller-arm 18 of switch 18 during vertical traversing movement of ring rail 10.

Referring now to H0. 4, switch 18 forms part of an electrical control circuit which, in addition to a power source (not shown), further includes an adjustable time-delay relay 36 having a pair of normally open contacts 36-1 and 36-2, and a master switch 38 which would normally control the energization of an element 40 forming part of the yarn-retrieving means of the piecing apparatus. When yarn retrieval is by suction, as shown, element 40 may constitute either the suctionmotor or valve which produces or directs suction flow through suction head 16.

OPERATION The operation steps of the method and apparatus of the invention will now be described.

At the outset of a doff or package-building operation of the spinning frame, ring rail It) occupies a lowermost position and bracket 22 and collar 32 occupy positions lower than those shown upon rod 24. As the package-building operation proceeds, ring rail 10 is moved slowly upwardly by the spinning frame's pick-motion mechanism as it is reciprocated vertically through a predetermined traverse by the frames builder-cam mechanism. Upon each upward displacement of ring rail 10 by the pick-motion mechanism, lower bracket arm 28 engages collar 32 and displaces the same upwardly an equal amount upon rod 24. Collar 32, and therefore the switch element 18 carried thereby, thus occupy throughout the package-building operation positions precisely correlated to the top of each traverse of ring rail 10. During each such traverse of ring rail 10, actuator element 20 engages rollerarm 18' of switch 18. Due to the one-way construction of switch 18, however, such engagement produces no result during upward traversing movement of ring rail 10 and actuating element 20. Assuming that there is no end-down" condition requiring servicing and that master-switch 38 (FIG. 4) is therefore open, such engagement during a downward traverse similarly produces no result other than an inconsequential momentary closing of switch 18.

Upon the occurrence and detection of an end-down condition at a delivery of the spinning frame, the movable carriage of the piecing apparatus would align itself with the delivery requiring servicing and a piecing cycle would be initiatedv Suction head 16 would be positioned upon ring rail 10, or otherwise made vertically movable in unison therewith, with its inlet opening closely adjacent the surface of bobbin-yarn package 12 immediately above spinning ring 14, and masterswitch 38 would be closed. At the moment when switch 38 is closed, as by a cam mechanism associated with the piecing apparatus, ring rail 10 might occupy any random vertical position in its traversing movement. For purposes of illustration, HQ 1 shows ring rail 10 then approximately midway through a downward traverse, and also shows actuating element 20 mounted by collar 30 and lock-bolt 34 in an upward adjustive position adjacent upper bracket arm 26. With the components thus positioned, suction flow through head 16 would not then commence, notwithstanding the closed condition of switch 38, since relay contact 36-2 is still open. However, as ring rail 10 nears the bottom of its traverse, actuator element 20 engages and trips roller-arm 18' of switch 18, momentarily closing switch 18 at a time just prior to when the inlet of suction head 16 spans the entire vertical extent of the chase-surface of package 12. The momentary closure of switch 18 closes its nonnally open contact 36l, locking in relay 36 for predetermined time interval, and also closes its normally open contact 36-2, completing a circuit through element 40 and commencing a suction-airflow through suction head 16. Irrespective of its precise vertical location upon the chase-surface of package 12, the yarn end is therefore quickly exposed to and retrieved by the suction flow through head 16. The airflow may therefore be terminated, by preset timing-out of relay 36 and the ensuing opening of its contacts 36-1 and 36-2, after a predetermined time interval only slightly greater than that required for retrieval of a yarn segment of the desired length, with the assurance that a satisfactory retrieval has been made.

During or upon completion of succeeding operations in the piecing cycle, master-switch 38 is again opened so as to restore the control mechanism to its original condition of readiness, for utilization when required at another delivery of the spinning frame having an end-down condition thereat. it will be noted that bracket 22 will be moved longitudinally along ring rail to such other delivery by rod 24, during movement of the main carriage of the piecing apparatus, and that the laterally offset position of bracket 22 permits free lateral movement of suction head 16 and/or other components (not shown) of the piecing apparatus toward and away from the bobbin-yarn package at any delivery being serviced.

Upon completion of each doff or package-building operation by the spinning frame, ring rail 10 is customarily lowered to an extreme downward position, either manually or by automatic means associated with the spinning frame. During such downward movement, upper bracket arm 26 engages switchmounting collar 32 and moves the same downwardly upon rod 24 in preparation for another cycle of package-building operation.

While collar 30 is preferably so adjustively positioned upon bracket post 22 as to occasion actuation of the suction or other yarn-retrieval means when ring rail 10 is in and closely adjacent the bottom of a downward traverse, as previously described, actuation when the ring rails is at any desired location in either an upward or downward traverse may be readily obtained simply by loosening lock-bolt 34 and repositioning collar 30 vertically of post 22, and/or by either everting switch element 18 or replacing the same with one tripped upon upward movement ofits roller arm 18'.

Although a specific embodiment of the invention has been shown and described, it is to be understood that this was for purposes of illustration only, and not for purposes of limitation, the scope of the invention being in accordance with the following claimsv That which is claimed is:

1. in an automatic yarn-piecing apparatus servicing a textile spinning frame or like machine having a spindle-mounted bobbin-yarn package encircled by a spinning ring, and a ring rail mounting said spinning ring and vertically movable during operation of the spinning frame through reciprocatory traverses at varying elevations, said apparatus having yarn-retrieving means vertically movable with the ring rail adjacent the surface of the bobbin-yarn package above the spinning ring for when actuated retrieving yarn from the package, the improvement comprising control means for actuating said yarnretrieving means, during each yarn-retrieving operation and irrespective of the random elevation of the particular reciprocatory traverse then being undergone by the ring rail, at a predetermined desired location of the ring rail within such particular reciprocatory traverse,

2. Apparatus as in claim 1, wherein said control means deactuates said yarn-retrieval means upon expiration of a predetermined time interval following said actuation thereof.

3. In the automatic end-down servicing of a textile spinning frame or like machine having a bobbin-yarn package encircled by a spinning ring carried by a ring rail vertically movable during operation of the spinning frame through reciprocatory traverses at varying elevations, wherein yarn-retrieving forces are applied to the package surface above the spinning ring, the improvement comprising commencing the application of said yarn-retrieving forces, during each servicing operation and irrespective of the random elevation of the particular reciprocatory traverse then being undergone by the ring rail, at a predetermined desired location of the ring rail within such reciprocatory traverse.

4. A method as in claim 3, wherein the application of said yarn-retrieving forces is commenced when the ring rail is adjacent the bottom of a downward stroke of a reciprocatory traverse.

5. A method as in claim 3, including terminating the application of said yarn-retrieving forces upon the expiration of a predetermined time interval following said commencement thereof.

6. In an automatic yarn-piecing apparatus servicing a textile spinning frame or like machine having a spindle-mounted bobbin-yarn package encircled by a spinning ring carried by the vertically traversing ring rail of the spinning frame, said apparatus having yarn-retrieving means vertically movable with the ring rail adjacent the surface of the bobbin-yarn package above the spinning ring for when actuated retrieving yarn from the package, the improvement comprising control means for actuating said yarn-retrieving means when the ring rail is at a predetermined desired location in its vertical traversing movement, said control means including a switch element, an actuator element adapted to actuate said switch element, means mounting one of said elements for traversing vertical movement in unison with the ring rail and for adjustive vertical movement relative to the ring rail, and means mounting the other of said elements for actuating engagement with said one element during said traversing movement thereof.

7. ln an automatic yarn-piecing apparatus servicing a textile spinning frame or like machine having a spindle-mounted bobbin-yarn package encircled by a spinning ring carried by the vertically traversing ring rail of the spinning frame, said apparatus having yarn retrieving means vertically movable with the ring rail adjacent the surface of the bobbin-yarn package above the spinning ring for when actuated retrieving yarn from the package, the improvement comprising control means for actuating said yarn-retrieving means when the ring rail is at a predetermined desired location in its vertical traversing movement, said control means including a switch element, and an actuator element adapted to actuate said switch element, means mounting one of said elements for traversing vertical movement with the ring rail, and means mounting the other of said elements in the path of said vertical traversing movement of said one of said elements for actuating engagement therebetween.

8. Apparatus as in claim 6, wherein said control means further comprises a control circuit including said switch element, a master switch element, a time-delay relay having a pair of normally open contacts, and a member effective upon energization to actuate said yarn-retrieval means, actuation of said switch elements energizing said relay and closing said normally open contacts thereof to energize said member and actuate said retrieval means for a predetermined time interval.

9. Apparatus as in claim 7, wherein said other-element mounting means mounts the same for vertical displacement with the ring rail of the spinning frame under the impetus of the pick-motion mechanism of the spinning frame.

10. Apparatus as in claim 9, including means carried by and movable with the ring rail and engageable upon vertical pickmotion displacement thereof with said other-element mounting means for imparting said displacement to said other element.

11. In an automatic yarn-piecing apparatus servicing a textile spinning frame or like machine having a spindle-mounted bobbin-yarn package encircled by a spinning ring carried by the vertically traversing ring rail of the spinning frame, said apparatus having yarn-retrieving means vertically movable with the ring rail adjacent the surface of the bobbin-yarn package above the spinning ring for when actuated retrieving yarn from the package. the improvement comprising control means for actuating said yarn-retrieving means when the ring rail is at a predetermined desired location in its vertical traversing movement, said control means including a bracket mounted for longitudinal movement relative to the ring rail and for vertical movement in unison therewith, vertically displaceable switch means mounted adjacent said bracket, first means carried by and vertically movable with said bracket for engaging and vertically displacing said switch means upon and in unison with vertical displacement of the ring rail of the spinning frame under the impetus of the pick-motion mechanism thereof, and second means carried by and vertically movable with said bracket for engaging and actuating said switch means during traversing movement of the ring rail of the spinning frame.

12. Apparatus as in claim 1, wherein said yarn-retrieving means includes a suction head movable vertically with the ring rail adjacent the surface of the bobbin-yam package above the spinning ring, and means for producing a suction airflow into said suction head upon actuation thereof, and said control means initiates suction airflow into said suction head.

i t I IF l 

1. In an automatic yarn-piecing apparatus servicing a textile spinning frame or like machine having a spindle-mounted bobbinyarn package encircled by a spinning ring, and a ring rail mounting said spinning ring and vertically movable during operation of the spinning frame through reciprocatory traverses at varying elevations, said apparatus having yarn-retrieving means vertically movable with the ring rail adjacent the surface of the bobbin-yarn package above the spinning ring for when actuated retrieving yarn from the package, the improvement comprising control means for actuating said yarn-retrieving means, during each yarn-retrieving operation and irrespective of the random elevation of the particular reciprocatory traverse then being undergone by the ring rail, at a predetermined desired location of the ring rail within such particular reciprocatory traverse.
 2. Apparatus as in claim 1, wherein said control means deactuates said yarn-retrieval means upon expiration of a predetermined time interval following said actuation thereof.
 3. In the automatic end-down servicing of a textile spinning frame or like machine having a bobbin-yarn package encircled by a spinning ring carried by a ring rail vertically movable during operation of the spinning frame through reciprocatory traverses at varying elevations, wherein yarn-retrieving forces are applied to the package surface above the spinning ring, the improvement comprising commencing the application of said yarn-retrieving forces, during each servicing operation and irrespective of the random elevation of the particular reciprocatory traverse then being undergone by the ring rail, at a predetermined desired location of the ring rail within such reciprocatory traverse.
 4. A method as in claim 3, wherein the application of said yarn-retrieving forces is commenced when the ring rail is adjacent the bottom of a downward stroke of a reciprocatory traverse.
 5. A method as in claim 3, including terminating the application of said yarn-retrieving forces upon the expiration of a predetermined time interval following said commencement thereof.
 6. In an automatic yarn-piecing apparatus servicing a textile spinning frame or like machine having a spindle-mounted bobbin-yarn package encircled by a spinning ring carried by the vertically traversing ring rail of the spinning frame, said apparatus having yarn-retrieving means vertically movable with the ring rail adjacent the surface of the bobbin-yarn package above the spinning ring for when actuated retrieving yarn from the package, the improvement comprising control means for actuating said yarn-retrieving means when the ring rail is at a predetermined desired location in its vertical traversing movement, said control means including a switch element, an actuator element adapted to actuate said switch element, means mounting one of said elements for traversing vertical movement in unison with the ring rail and for adjustive vertIcal movement relative to the ring rail, and means mounting the other of said elements for actuating engagement with said one element during said traversing movement thereof.
 7. In an automatic yarn-piecing apparatus servicing a textile spinning frame or like machine having a spindle-mounted bobbin-yarn package encircled by a spinning ring carried by the vertically traversing ring rail of the spinning frame, said apparatus having yarn retrieving means vertically movable with the ring rail adjacent the surface of the bobbin-yarn package above the spinning ring for when actuated retrieving yarn from the package, the improvement comprising control means for actuating said yarn-retrieving means when the ring rail is at a predetermined desired location in its vertical traversing movement, said control means including a switch element, and an actuator element adapted to actuate said switch element, means mounting one of said elements for traversing vertical movement with the ring rail, and means mounting the other of said elements in the path of said vertical traversing movement of said one of said elements for actuating engagement therebetween.
 8. Apparatus as in claim 6, wherein said control means further comprises a control circuit including said switch element, a master switch element, a time-delay relay having a pair of normally open contacts, and a member effective upon energization to actuate said yarn-retrieval means, actuation of said switch elements energizing said relay and closing said normally open contacts thereof to energize said member and actuate said retrieval means for a predetermined time interval.
 9. Apparatus as in claim 7, wherein said other-element mounting means mounts the same for vertical displacement with the ring rail of the spinning frame under the impetus of the pick-motion mechanism of the spinning frame.
 10. Apparatus as in claim 9, including means carried by and movable with the ring rail and engageable upon vertical pick-motion displacement thereof with said other-element mounting means for imparting said displacement to said other element.
 11. In an automatic yarn-piecing apparatus servicing a textile spinning frame or like machine having a spindle-mounted bobbin-yarn package encircled by a spinning ring carried by the vertically traversing ring rail of the spinning frame, said apparatus having yarn-retrieving means vertically movable with the ring rail adjacent the surface of the bobbin-yarn package above the spinning ring for when actuated retrieving yarn from the package, the improvement comprising control means for actuating said yarn-retrieving means when the ring rail is at a predetermined desired location in its vertical traversing movement, said control means including a bracket mounted for longitudinal movement relative to the ring rail and for vertical movement in unison therewith, vertically displaceable switch means mounted adjacent said bracket, first means carried by and vertically movable with said bracket for engaging and vertically displacing said switch means upon and in unison with vertical displacement of the ring rail of the spinning frame under the impetus of the pick-motion mechanism thereof, and second means carried by and vertically movable with said bracket for engaging and actuating said switch means during traversing movement of the ring rail of the spinning frame.
 12. Apparatus as in claim 1, wherein said yarn-retrieving means includes a suction head movable vertically with the ring rail adjacent the surface of the bobbin-yarn package above the spinning ring, and means for producing a suction airflow into said suction head upon actuation thereof, and said control means initiates suction airflow into said suction head. 